High-frequency furnace



July 10, 1928.

H. C. RENTSCHLER ET AL HIGH FREQUENCY FURNACE Filed Jan. 5, 1925 INVENToRs c RENTscHLER W.. DEN

ATrQRNEY HARVEY JgH Patented July 10, 1928.

UNITED STATES PATENT OFFICE.

HARVEY CLAYTON RENTSCHLER AND IJERSEY, ASSIGNORS T0 WESTING PENNSYLVANIA..

Applicatie JOHN WESLEY MARDEN, OF EAST ORANGE, NEW HOUSE LAMP COMPANY,

A. CORPORATION OF HIGH-FREQUENCY FURNACE.

This invention relates to furnaces and more particularly to tion furnaces. l

The present invention high frequency inducis a continuation in part of application Serial No. 717,940, filed June 5, 1924, assignedto the same assignee as the present application.

It also embodies certain specific improvements in the high frequency in illustrated in Patent duction furnace No. 1,480,301 likewise described and high frequency currents circulated. Within this support upon which is placed compound to be heated.

are adapted to be coil is positioned a the metal or The vessel is connected to an exhaust system for the purpose of producing a high vacuum therein.

The device described after, finds special appl more fully hereinication in the heat treatment of metals which readily. oxidize such, for example, as thorium,

the like, usually the rare or refractory metals.

coniuni and larly useful in sintering or uranium, zirreferred to as It is particufusing such metals so as to obtain a uniformly coherent, pure and ductile product.

One of the features of tion relates to the provision teiior structure which is so the present invenof a unitary indesigned as to provide for accurately positioning `the support and metal thereon Within the high frequency coil so as heating as Well as the effect.

One of the principal to obtain uniformity of maximum heating and important features of our invention consists in the provision of a supporting di is composed of a materi stand the exceedingly prevailing in tion and Which, at

the furnace the same time,

sk or crucible which al Which Will Withhigh temperatures during its opera- Will not contaminate the material'undergoing treatmen It should be appreci treating uranium, peratures are cause of the avidity of oxygen, etc., it is .impor rial should that the maximum hea the rai'e metals,

and the like, exceedingly high temdesirable and ated thatvin heatsuch as thorium,

furthermore, besuch materials for tant that the matebe supported in such a manner ting effect may be of the furnace, some n lyed January 5, 1925. Sera1 No. 475.

obtained and also so that there is no likelihood of their being contaminated. This is especially true of the very active rare metals thorium and uranium, for the reason that these metals reduce many refractories, such as lime, for example, thus making the use of a support suoli as thoria desirable.

One of the special advantages of our furnace is in the production of large masses of coherent, ductile material in special form, such as large X-ray targets in disk form Which, when subjected to high heat treatment, Will be preserved in their pure metallic condition.

Therefore, it is an object of the present invention to provide a form of support whereby uniform heat treatment may be given a large mass of material.

Another object of the invention is to provide a support Which is of such a nature that it does not affect the material undergoing treatment at the high temperatures prevailing during the treatment.

Another object of the invention is to provide a furnace of the high frequency induction type in Which the specimen undergoing treatment may be so positioned with respect to the heat inducing member as to obtain the maximum heating effect.

A still further object of the invention is to provide a more efficient and inexpensive furnace construction.

Other objects of the invention Will be apparent from the following description.

Referring to the drawings,

Fig. 1 is a view in elevation ofone form parts beingl shown in section;

Fig. 2 is an enlarged elevational view partly broken away, of the heating element' and support; and,

Fig. 3 is an elevational view of a support With a large mass of a metal thereon, the metal being given the form of an X-ra'y target of disk construction, a cover being provided to conserve the heat.

The furnace comprises essentially a holloW body or chamber 1 of any suitable shape and material, preferably glass, an induction member or coil 2, of tungsten or other suitable material, and a support 3 for the material undergoing treatment.

The envelope may comprise a bulbous portion 4 having a tubular neck 5 terminating in an outwardly llared mouth 6 toform a seat 7 for a closure 8 to be described more fully hereinafter. The seat 7 of the mouth 6 is carefully ground upon its inner surface so that the closure 8 makes a hermetic joint therewith. To the upper end of the bulbous portion 4 there is secured a tube .9 which is connected with any suitable type of efficient exhaust apparatus capable of producing an exceedingly high vacuum within the cha mber. The tube /9 is in open communication with the interior of the chamber 1.

The closure 8 comprises a' tubular portion 11 of glass having an enlargement 12 terminating in an outwardly extending tubular extension 13. A cooling fluid mayl be projected into the tubular extension 3 to maintain the closure 8 cool. The enlargement 12 has a conical portion 14 correspending in shape to the seat 7, but of slightly smaller diameter so as to snugly fit within the mouth 6 of the envelope. This conical portion of the closure is ground in a manner similar to the seat 7 so as to obtain a hermetric seal, although it may be found desirable, as has been done in practice, to place an evenly deposited layer of stopcock grease upon the seat 7 andV conical portion 14, whereby an air tight joint is obtained. lVhere grease is objectionable, talc may be used.

The closure 8 as well as the envelope l is made of glass, -preferably a hard glass such as a silica or quartz glass.

Extending inwardly from the tubular portion 11 are two spaced-apart small tubular extensions 15 and 16, the ends of which are formed into two presses 17 and 18. vIn the presses are sealed tungsten rods 19 and 2l, which serve as conductors of the high frequency current as well as supports for the high frequency coil'or induction member 2.

The lower portions of the vtungsten rods 19 and 21 extend through the tubular exf tensions 15 and 16 and are brazed or otherwise electrically united at 22 and 23 to leadin wires 24 and 25, formed of stranded twisted copper, which latter may be connected to any suitable source of high frequenc'y current supply. A. sleeve of glass 26 surrounds a portion of the conductor 24 to insulate the same from the other lconductor 25.

Referring to Fig. 2, it will be observed that the high frequency coil or induction member 2 consists o-f a helix made up of closely spaced turns of wire, preferably tungsten. The lower end of the helix terminates in a downwardly extending leg 27 and the upper end in a downwardly extending leg 28. These legs are removably secured in clamps 29 and 31. sleeves of suitable conducting metal, the ends of the supporting rods 19 and 21 and the ends of the legs 27 and 28 being secured facilitates the The clamps consist of therein by means of screws 32 or the like.

The support 3 for the material to be heattreated comprises a plurality of upwardly extending' and outwardly flaring arms 33, having their lower ends secured in a sleeve 34, their upper ends being free. A supporting rod 35 is centrally disposed within the sleeve 34 and removably fastened therein by screws 36. The lower end of the rod 35 is embedded in a block of insulating material 37, such as glass. Another supporting rod 38 has one end also embedded in the block 3T, such end being spaced from the end of the rod 35, so that the two rods are separated b v insulation furnished by the block 37. The lower end of the rod 38 iS removably secured in one of a plurality of openings 39 in a clamp 41. .Fastening means 42 such as screws may be employed to secure the rod 38 in any position of adjustment. The clamp 41 may be adjustably secured to the tungsten supporting rod 19 by Screws 43,-

the rod 19 passing through an opening in the clamp. It will thus be apparent that the support 3 may be vertically adjusted with respect to the induction member 2, and also adjusted horizontally by disposing the supporting rod 38 in one of the the clamp 41. By reason of the insulating block 37, the current passing through the tungsten rod 29 is prevented from passing through the support 3 and the material resting thereon.

positioning of the specimen undergoing treatment within the induction member 2 so as to obtain the maximum heating effect. lt is obvious, however, that other means of adjustment, apparent to those skilled in the art, may be provided.

The support proper for the material to be treated and which we have found to be the most efficient for our purpose, may be one preferably consisting of thoria, zirconia, or the like, free from impurities Which may melt or volatilize during the treatment and which will not contaminate or combine with the metal undergoing treatment or be effected thereby. rl`he method described and claimed in copending application Serial No. 542,134, filed March 8, 1922, assigned to the same assignee vas the present application, may be employed to produce these'supports.

The support consists in a preferred form of a shallow cup-shaped body 44 of thoria which is inverted and placed upon the ends of the arms so that the latter engage the inner sides of the downwardly extending wall 45 of the support. The support is thus firmly held in position. v

As illustrated in Fig. 1, the specimen 46, to be treated` mav be placed directly upon the support 44. This material when placed upon the support may consist of a pellet or cake of the powder of the metal pressed into a compact mass. Upon heat-treating thoropenings 39 of- The structure thus provided oughly the metal may be sintered or/and fused, and we have found in instances where the metal has been melted that it draws away from the support yand does not run into it, and forms into a globular-shaped pellet, such as indicated in Fig. -1. Crlhis shows -the purity of the metal and its freedom from contamination.

In Fig. 2 we have illustrated in dotted outline 47, a Crucible formed of thoria, or the like. The material 'undergoing treatment` may be placed within the crucible and melted. The crucible may be so shaped as to impart to the material any desired configuration, thus, in a sense constituting a mold in which the material is cast to form.

In treating large masses 48l or specimens of rare metals to form, for example, large disk targets for X-ray tubes and the like, the

arrangement illustrated in Fig. 3 may be' employed. In this construction an additional support or cover 49 may be provided. The cover may be placed directly upon the specimen or target. By means of this arrangement the specimen is positioned in suoli a manner as to diminish the heat loses as the support and cover serve as heat retainersto prevent radiation and thus permit the attainment of higher temperatures as Well as more uniform heating of the specimen. It is possible with this form of support to uniformly heat a very large mass of thorium and the like to form a homoge-` neous body of metal which is ductile throughout.

The operation of the furnace may be readily inferred from the preceding description.

It is obvious that the material support may be made in a variety of shapes, such as disks, crucibles and the like.

Modifications ofthe foregoing invention may suggest themselves to those skilled in the art, but such as fall within the scope of the appended claims are contemplated as forming part of our invention.

W'hat is claimed is:

l. A furnace comprising an hermetically sealed vessel, means connecting said vessel to an exhaust pump, a removable mount for said vessel, said mount comprising a hollow tubular member open at one end and terminating in a press at the other end, a plurality of leading-m wires sealed in said press, main supports connected to said leading-in wires, a high frequency induction coil carried by said supports, anda material support connected to one of said main' supports, said material support being composed in part of a material Whichdoes not react with the material undergoing treatment.

2. A furnace comprising an hermetically sealed vessel, means connecting said vessel to an exhaust pump, a removable mount for said vessel, said mount comprising a hollow tubular member open at one end and terminating in a press at the other end, a plurality of leading-in wires sealed in said press, main supports connected to said leading-in wires, a high frequency induction coil carried by said supports, anda material support connected to one of said main supports, said material support being composed in part of a material whichdoes not react with the material undergoing treatment, said material support being adjustably secured to said main support.

3. A furnace comprising an hermetically sealed vessel, means connecting said vessel to an exhaust pump, a removable mount for said vessel, said mount comprising a hollow tubular member open at one end and terminating in a press at the other end, a plurality of leading-in wires sealed in said press, mam l supports connected to said leading-in wires, a high frequency induction coil carried by said supports, and a material support connected to one of said main supports, said material support being composed in part of a material which does not react with the material undergoing treatment, said high frequency coil being removably secured to said main supports.

4. A furnace comprising an hermetically sealed vessel, means connecting said vessel to an exhaust pump, a removable mount for said vessel, said mount comprising a hollow tubular member open at one vend and terminatingin a press at the other end, a plurality of leadingn wires sealed in said press, main.4

supports connected to said leading-in wires, a high frequency induction coil carried by said supports, and a material support connected to one of said main supports, said material support being composed in part of a material which does not react with the material undergoing treatment, saidy material support being adjustably secured to said main support so as to be capable of movement in the direction of the -longitudinal axis of the mount and in a plane transverse thereto.

5. A furnace comprising an hermetically sealed vessel, means connecting said vessel to an exhaust pump, a removable mount for said vessel, said mount comprising a hollow tubular member open at one end and terminating in a press at the other end, a plurality of leading-in wires sealed in said press, main supports connected to said leading-in wires, a high frequency induction coil carried by said supports, and a material support connected to one of said main supports, said material support being composed of' thoria.

In testimony whereof, we have hereunto subscribed our names this 3rd day of J anuary 1925,

HARVEY CLAYTON RENTSCI-ILER. JOI-IN WESLEY MARDEN. 

